Lenders determine how much mortgage you can afford based on your income, credit score, and current debts. Each situation is different but in general, lenders allow up to a 43 – 50% debt-to-income ratio. Your mortgage (principal, interest, real estate taxes, home insurance, and mortgage insurance) plus any existing debts, such as credit cards, car loans, or personal loans shouldn’t exceed 43% – 50% of your gross monthly income (income before taxes).